This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-187744.
The present invention relates to a control system of a vehicle equipped with a continuously variable transmission, specifically to a vehicle control system suitable for the standardization and rationalization, etc., of plural component units that are incorporated in the vehicle, including the continuously variable transmission.
An integrated control system is proposed to achieve a stabilized control of the whole vehicle, by making up the system so as to mutually exchange data between control, units provided individually with these plural functional units.
This type of the integrated control system connects control calculation units of the functional units each other by way of a communication line. The system is configured so that the control calculation units can mutually use calculation values and detection values and so forth that the control calculation units each acquire.
However, in such a configuration that the functional units each do not hold completely independent control units, some functional units have to wait for transmissions of the calculation values and detection values that the other functional units acquire. The functional units have to perform the individual calculations. Accordingly, there is a possible apprehension of delay in response that does not occur in the conventional mode that provides the control calculation units to the functional units each to determine the behavior of the vehicle and performs the control operation according to that behavior.
Especially, the delay in response given to the transmission control of a vehicle comes out in a form of an operational delay on the transmission side with regard to a gear shifting demand on the vehicle side. If a multistage transmission that gradually varies the axle torque during a gear shifting is adopted as an automatic transmission, when a gear shifting command to another stage interrupts by any reason during a shifting operation, the foregoing delay in response will lead to an unstable shifting control, and generate a shock to the vehicle due to abrupt variations of the axle torque during a gear shifting.
It is therefore an object of the invention to provide a vehicle control system that is suitable for the integrated control of a vehicle equipped with a continuously variable transmission and for reduction of shift shock caused by the transmission.
It is another object of the invention to provide a vehicle control system that is suitable for standardization and rationalization and so forth of plural component units of the vehicle.
According to the present invention, a command value of a gear ratio of a continuously variable transmission equipped in a vehicle is calculated, an input torque to the continuously variable transmission is detected, and the gear ratio of the continuously variable transmission is controlled on the basis of these calculation value and detection value. A gear ratio control unit having a function of gear ratio control and one or plural function units for the gear ratio calculation and the torque detection are constructed in different units each other. Those units are mutually connected through a communication line capable of data transmission. The gear ratio control unit does not carry out the calculation of the gear ratio, etc., and the gear ratio control unit simply controls the gear ratio of the continuously variable transmission on the basis of the command value of the gear ratio and the input torque transmitted to the gear ratio control unit through the communication line.
Accordingly, when loading the gear ratio control unit in a vehicle, even though the type and the engine of the vehicle is varied, the system of the invention does not need to tune the gear ratio control unit one by one in correspondence therewith. Therefore, the system is able to configure the continuously variable transmission and the gear ratio control unit independently of the type of the vehicle, which achieves standardization (generalization) of the continuously variable transmission in terms of both the hardware and the software. The gear ratio calculation and the torque detection are required to modify the control variables and so forth that they use, depending on the type of the vehicle. However, if both of these means are configured in one functional unit, the parts to be modified can be concentrated in both aspects of the hardware and the software. In this manner, it is convenient to concentrate the parts to be modified in respect of the system design and the management.
Further, an achievement of the standardization of the continuously variable transmission will lead to carrying out a development of the control system of the continuously variable transmission and a development of the control system of the engine independently in parallel. Therefore, a development of the gear ratio control unit in conformity to the continuously variable transmission and a development of a new logic that the gear ratio control means performs, and so forth will be carried out without needing to wait for a development of an engine. The final adjustment on mating a continuously variable transmission with an engine can be carried out swiftly. Accordingly, the total term for developing a vehicle equipped with a continuously variable transmission can be shortened.